A lot can change in 25 years! Take a trip down memory lane and relive these guests' earlier Oprah Show appearances.

Kirstie Alley Donned a Bikini

It was one of the most anticipated moments in The Oprah Winfrey Show: actress Kirstie Alley, onstage, in nothing but a bikini and heels.

Two years before the big reveal, in November 2004, Kirstie opened up to Oprah about her struggle with weight. Once a slender Hollywood starlet, she'd become a target for the paparazzi and her private battle had become very public news. "Honestly, I didn't know how fat I was," she said. "Thanks to the tabloids I went, 'Damn, girl, you're fat!'"

Kirstie quit smoking the very next day and decided to change her life. Determined to drop a few dress sizes, she became a spokesperson for the Jenny Craig weight loss program. After losing 33 pounds, Kirstie said she burned her "fat pants." Over the next two years she continued to update Oprah on her progress, first revealing her diet plan and then showing off the dance moves that were helping her shed the weight.

The big bikini reveal came in 2006. After losing 75 pounds, Kirstie walked onstage in nothing but a red lace two-piece. It was a moment everyone was talking about. "You look beautiful," Oprah told Kirstie when she strutted her stuff.

In the years since, Kirstie's weight has continued to fluctuate, and she's appeared on The Oprah Show to talk about "falling off the wagon" and her short-lived reality show Kirstie Alley's Big Life. These days, Kirstie is competing on Dancing with the Stars and says she's happily shedding the pounds. "I worked hard to lose, but it became something more for me," she said. "It was a spiritual journey."